SLP Mountain Helixes are designed for hillclimbing and deep snow riding with the best combination of upshift and backshift possible. They use a multi-angle design to get the most from your engine. The initial angle is aggressive for maximum upshift in order to get the sled on top of the snow quickly. The finish angle insures optimum backshift for running in a variety of elevations and snow conditions. The transition between these two angles is a generous radius providing smooth, seemless shift characteristics. The initial angle length is adjustable by adding or subtracting shims. (2 shims included).....Sold per each.Super Tough! Super Slippery! Super Backshift! Use #40-9 Super Slippery™ Buttons for an awesome combination!